This invention relates generally to waste compactors, and, in particular, to waste compactors for receiving inputs of waste and periodically compacting those inputs.
While waste compactors have been known for domestic use, such machines can also be useful in fast food restaurants and shopping malls for compaction of loose garbage. In general, refuse from fast food restaurants such as may be deposited in waste containers has a relatively low density. It is desirable to compact this garbage for several reasons. First, very low density garbage such as paper cups, hamburger containers, tissue napkins, and the like, can fill waste containers in high usage areas in a relatively short period of time. It is inefficient for staff to have to remove full containers more frequently than necessary. Costs associated with large garbage containers, such as may be transported to a dumpsite or emptied into a large truck, tend to vary as the number of times they are filled. In consequence it is advantageous to compact the garbage to lengthen the time interval between removals, and to reduce the cost of dumping the materials.
The use of such machines in a public or quasi-public space, such as in the relatively large garbage containers used in restaurants and shopping malls poses challenges that may not be as prevalent in the small domestic garbage compactors. First, the overall weight of the compacted mass must be kept to a level that is safe for workers, generally in the range of 35 lbs. Some jurisdictions limit the allowable weight of garbage bags to 25 lbs. In one known unit, a system of hydraulic cylinders is used to compress the waste material. In that known system, a unit having an overall size of 51xe2x80x3 height, 24 xc2xdxe2x80x3 width and 22xe2x80x3 depth accomodates a bin that is 19 xc2xexe2x80x3 deep, 18xe2x80x3 wide and 17xe2x80x3 high. This system can, under some conditions, compress more than 100 lbs of garbage in a single load. This is well in excess of what an employee is generally expected, or allowed by law in some jurisdictions, to lift.
In general garbage compactors have a receptacle for receiving garbage, and a compression unit for compacting the garbage after a certain amount has been collected in the receptacle. The compression units generally force a platen to extend into the garbage, causing it to compress. It is important that it be highly improbable, preferably impossible, for the compression unit to operate at any time that a person""s hands could be caught in the machinery.
The risk of injury is highest in three instances. The first is when a person is emptying garbage into the input chute of the receptacle. The second is when a person is removing collected garbage or cleaning the inside of the unit. The third is when the compaction machinery is in operation. It is also important that objects not become stuck in the input chute when the compression unit is in the middle of operation, such that it cannot retract. Similarly, it is important to be able to extend the compression unit to permit cleaning, without the risk of having the units retract in the middle of the cleaning operation.
A further problem is the tendency of sticky liquids or gums to build up inside the garbage receptacle. In one known machine a solenoid whose purpose was to lock an input chute door during operation compression became gummed over with sticky materials, and in some instances would not lock the door. Another problem with a known machine was that the compression unit had a hinged pressure plate. On the return stroke the hinged plate had a tendency to flip liquids that collected on top of the plate up into the innards of the machinery space. The machinery space was relatively inaccessible for cleaning.
Whereas a homeowner can explicitly decide when to cause a trash compactor to cycle, it may be advantageous for a machine in a public space, a mall, or a restaurant to operate automatically. On one hand customers may not operate the machine when it is required, and on the other hand, they may not operate it correctly in any event, possibly with unfortunate consequences. Further, a person approaching a public garbage receptacle may be carrying a cafeteria tray. It may be awkward for that person to open the garbage chute with one hand while holding the tray with the other. A person may need both hands to carry the tray, particularly if the user is a child. Alternatively, a person having only one arm may find opening the chute and dumping the tray a difficult task. It would be advantageous to have an input chute that opens automatically. However, once the chute is open, it would not be advantageous to have it close while either a tray or a person""s hand was still in the chute.
It is known to use a scissors jack mechanism to drive a compression plate, typically downward, into the garbage. Previous scissors jacks have at times shown a tendency to twist or wander, particularly if the garbage has local discontinuities, that is, it compresses more easily on one side than another. If the wander, or tolerance build-up, is too great, the mechanism may ride against the side of the receptacle or other structure. This can lead to wear and damage to the structure, and is undesirable.
In a first aspect of the invention there is an apparatus for compacting refuse. It has a compression member moveable to compress refuse collected in a receptacle, a drive connected to move the compression member, a structure to which the drive is mounted, and a sensor for gauging the level of refuse in the receptacle. The drive and the compression member are operable in response to a signal from the sensor.
In an additional feature of the invention, the apparatus includes a housing enclosing the compression member, the drive and the sensor. The housing has an accommodation for the receptacle and an inlet for admitting refuse to the receptacle. The apparatus has an inlet closure member operable to lock the inlet during operation of the compression member.
In another additional feature of that aspect of the invention, the apparatus includes the receptacle. In a still further additional feature of the invention, the compression member is moveable to an inactive position. The apparatus includes a proximity sensor connected to cause the inlet closure member to open when the compression member is in the inactive position and the proximity sensor senses an object near the inlet.
In still another further additional feature of the invention, the apparatus is responsive to resistive loading of the compression member by the refuse. In yet another additional feature of the invention, the compression member is constrained by any one of a load limit and a displacement limit.
In still another additional feature of the invention, the compression member is constrained by a receptacle full limit condition. The apparatus has a signaling device for signalling to an operator that the receptacle full limit condition has been reached. In still yet another additional feature of the invention, the apparatus includes a weight sensor mounted to gauge the amount of refuse in the receptacle and the xe2x80x9creceptacle fullxe2x80x9d limit condition is signalled by the weight sensor.
In another additional feature of the invention, the apparatus further comprises a load sensor for gauging the resistance opposing the drive and a sensor for gauging displacement of the compression member. The xe2x80x9creceptacle fullxe2x80x9d limit condition is determined as a function of signals received from the load sensor and from the sensor for gauging displacement of the compression member.
In yet another additional feature of the invention, the compression member is moveable to engage and disengage the refuse. The apparatus has a wiper mounted to discourage refuse from clinging to the compression member when the compression member is disengaged from the refuse. In another additional feature of the invention, the drive is free of hydraulic elements.
In yet another feature of the invention, the drive includes a scissors mechanism having a pair of input legs extending from a common fulcrum. The input legs have input feet mounted to the structure. The mechanism also has a pair of output legs having output feet mounted to the compression member. One of the input feet is mounted to pivot about a first axis whose location is fixed relative to the structure. The compression member is constrained to move in a direction parallel to the bisector of the angle defined between the input legs.
In still yet another feature of the invention, one of the output feet is constrained to pivot about a second axis whose location is fixed relative to the compression member, the first and second axes being parallel. In a further additional feature of the invention, one of the output feet is constrained to pivot about a second axis whose location is fixed relative to the compression member, the first and second axes being parallel and lying in a common plane parallel to the bisector.
In still yet another additional feature of the invention, the drive includes a scissors mechanism having a pair of input feet mounted to the structure and a pair of output feet mounted to the compression member. One of the input feet is constrained to pivot about a first axis whose location is fixed relative to the structure. The other of the input feet is constrained to follow a first linear path lying on a radius from the first axis. One of the output feet is constrained to pivot about a second axis, whose location is fixed relative to the compression member. The other of the output feet is constrained to follow a second linear path lying on a radius from the second axis, the first and second axes being parallel and lying in a common plane, the first and second paths being parallel, the others of the input and output feet both lying to the same side of the plane, the paths being perpendicular to the plane.
In a further additional feature of the invention, the drive comprises a pair of the scissors mechanisms mounted in parallel. In still a further additional feature of the invention, the others of the output feet of the pair of parallel scissors mechanisms each has one of a pair of gears mounted thereto. The gears are mounted to a common shaft parallel to the second axis. Each of the gears is constrained to mesh with a linear rack mounted to the compression member.
In yet a further additional feature of the invention, the drive further includes a motor, a screw driven by the motor, and a yoke engaged to be moved by the screw. The yoke has a screw follower mounted to ride on the screw, a drag member connected to move the other of the input feet and a resilient member mounted to transmit motion between the screw follower and the drag member.
In another aspect of the invention, there is a method of compacting refuse in a refuse receptacle with a compression member, gauging the level of refuse in the receptacle, sending a signal when the refuse is ready to be compressed, moving the compression member to compress the refuse in response to the signal and governing the movement of the compression member according to the resistance presented by the refuse.
In an additional feature of the invention, the step of governing includes monitoring load feedback from the compression member. In another additional feature of the invention, the step of monitoring load feedback includes monitoring the current of a motor driving the compression member.
In a still further additional feature of the invention, the step of moving includes extending the compression member on a compression stroke, and the step of governing includes ending the compression stroke in response to one of the conditions chosen from the set of conditions consisting of (a) a full stroke displacement limit condition; (b) a load limit condition; and (c) a xe2x80x9creceptacle fullxe2x80x9d limit condition.
In a yet further additional feature of the invention, the step of governing includes gauging the weight of refuse in said receptacle. In a still further additional feature of the invention, the method includes the step of preventing more refuse from entering the receptacle when the compression member is in motion. In another further additional feature of the invention, the step of moving the compression member includes returning the compression member to an initial position. In an additional feature, the step of returning includes cushioning the arrival in the initial position.
In a yet further additional feature of the invention, the step of gauging includes the steps of waiting for refuse to be put in said receptacle. In another further feature of the invention, the step of waiting includes the steps of sensing for persons near said receptacle, and opening an accessway to permit refuse to enter the receptacle when persons are near the receptacle.